The present invention relates to an apparatus for driving controlling displacement of a plurality of yarn feeders arranged in a flat knitting machine.
Reflecting widely diversified fashions of garments in recent years, those modern knits including sweaters knitted by operating flat knitting machines contain a variety of color yarns and various kinds of yarns.
Any of those conventional flat knitting machines available for knitting color yarns of various kinds are furnished with a plurality of carriages which are secured to needle beds in order to adjust movement of knitting needles into and out of a knitting zone. In addition, a plurality of yarn feeders are slidably installed in the front and on the back of a plurality of yarn-guide rails which are secured above and in the longitudinal direction of those needle beds. In this case, it is necessary for respective yarn feeding apertures at the bottom tips of those yarn feeders to properly feed yarns at predetermined positions close to the tips of knitting needles when those knitting needles on the needle bed project themselves at the knitting position.
However, when setting all the yarn feeding apertures of those yarn feeders at predetermined positions close to the tips of knitting needles while knitting needles project themselves at the knitting position, those yarn feeding apertures collide with each other on the way of shifting positions of those yarn feeders which presents a critical problem to solve.
Now, therefore, in order to solve this problem, the applicant of the present invention previously proposed prior art related to a knitting yarn feeding system as disclosed in the Japanese Laid-Open Patent Publication No. 50-13657 of 1975. The disclosed prior art features the structure described below.
A plurality of carriages for adjusting positions of knitting needles into and out of a knitting zone are installed on a plurality of yarn guide rails disposed above and in the longitudinal direction of needle beds. An operating pin is also provided, which is capable of controllably moving itself in the vertical direction from those carriages to the yarn feeders.
A coupling recess available for engagement with the operating pin is provided on the top surface of each yarn feeder. Concretely, when the operating pin which is engaged with the coupling .recess moves in association with yarn feeders, the operating pin forcibly opens a link in resistance against attractive energizing force of a spring in order to lower yarn feeding apertures on the bottom tip of respective yarn feeders down to a predetermined position close to the tips of the knitting needles. On the other hand, when the operating pin engaged with the coupling recess is not accompanied with yarn feeders, the operating pin attracts the link by an attractive energizing force of a spring to lift the yarn feeding apertures at the bottom tips of respective yarn feeders, thus preventing yarn feeding apertures of other remaining yarn feeders from interferring with each other.
Nevertheless, since the preceding prior art disclosed in the above-cited Japanese Laid-Open Patent Publication No. 50-13657 of 1975 is structured to shift yarn feeders by forcibly opening a link composed of two pairs of levers and pins in resistance against tensile force of a spring on the way of shifting an engaged rod available for shifting a yarn guide unit, when the spring exerts such tensile force stronger than a sliding resistance generated by yarn feeders, those yarn feeders are transferred in such a state in which the link is not fully spread, in other words, in such a state in which yarn feeding apertures are not fully down.
Furthermore, since the tensile force of the spring is exerted in the direction of proceeding yarn feeders, even when the engaged rod available for shifting a yarn guide unit halts at the predetermined position, due to effect of a tensile force generated by the spring, yarn feeders are obliged to travel themselves furthermore, thus making it difficult for the flat knitting machine to correctly control the shifting movement and stopping operation of the yarn feeders.